public class Droites
{
	public static void main (String args[]) 
	{
		droite(1,1,4,4);
		System.out.println(appartient(1,1,0,0,0));
	}
	public static void droite(double x1, double y1, double x2, double y2)
	{
		double a = -(y2-y1)/(x2-x1);
		double b = 1;
		double c = y2 + (a * x2);
		System.out.println(a+"x +"+b+"y = "+c);
	}
	public static boolean appartient(double a, double b, double c, double x, double y)
	{
		return (c == a*x+b*y);
	}	
}

